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08 March 2019

An international group of scientists have published the first study using data from the Copernicus Sentinel-3 Delay-Doppler altimeter, to monitor Antarctic Ice Sheet change.

The Sentinel-3A satellite of the European Union's Copernicus Programme was launched on 16 February 2016, followed by Copernicus Sentinel-3B on 25 April 2018. Each satellite provides coverage up to a latitude of 81.35°, yielding regular, monthly observations of much of Earth's polar ice sheets.

Although radar altimeter satellites have monitored the polar regions for over two decades, Copernicus Sentinel-3 is unique, because it is the first mission to operate in high-resolution Delay-Doppler (or Synthetic Aperture Radar—SAR) mode across the entire ice sheet.

In this study, scientists provide the first comprehensive evaluation of Copernicus Sentinel-3A elevation measurements over Antarctica. Through detailed analysis of measurements over the smooth flat surface above subglacial Lake Vostok, and comparisons to data collected during airborne campaigns, they are able to assess the accuracy of these new measurements, and their utility for glaciological study.

The researchers also demonstrate, for the first time, the capability of Copernicus Sentinel-3 to track changes in ice sheet surface elevation, using data collected over the first two years of routine operations.

This analysis is an essential first step towards utilising the Copernicus Sentinel-3 satellites for systematic monitoring of ice sheet volume change, mass balance, and contribution to sea level rise, thereby complementing the invaluable record currently provided by ESA's CryoSat satellite.

Although the Copernicus Sentinel-3 SRAL altimeter does not have the unique 'dual view' interferometer of CryoSat, it does operate in high-resolution Delay-Doppler mode over the whole ice sheet, including the vast and inaccessible Antarctic interior.

In this study, the researchers show the exciting potential of these new high-resolution measurements, in combination with the regular monthly monitoring schedule, to detect glaciological changes in these regions, such as the draining of subglacial lakes buried beneath several kilometres of ice.

Key Findings

Over the low slope regions of the ice sheet interior, the study finds that Copernicus Sentinel-3 has a high accuracy, of the order of 10 cm, with ~98% of the data validated being within 50 cm of airborne validation measurements

Across the steeper and more complex topography of the ice sheet margin, the accuracy decreases, although ~60-85% of validated data are still within 1 metre of co-located airborne elevation measurements

The researchers show that with only two years of available data, it is possible to resolve known signals of ice dynamic imbalance, particularly across the fast-flowing West Antarctic ice streams flowing into the Amundsen Sea

The study also demonstrates for the first time that Copernicus Sentinel-3 is able to detect evidence of subglacial lake drainage activity beneath the East Antarctic Ice Sheet

These results demonstrate the early promise of the Copernicus Sentinel-3 mission as a tool for monitoring ice sheet change.

"Having started prior to the satellite launch by simulating Copernicus Sentinel-3 data using CryoSat, we have now reached a position where we are able to analyse Sentinel-3 data itself. For the first time we can clearly see its potential for monitoring ice sheets, and to act as a dependable complement to specialist polar missions like CryoSat—which is a really exciting moment for the whole team", added McMillan.

About the Copernicus Sentinels

The Copernicus Sentinels are a fleet of dedicated EU-owned satellites, designed to deliver the wealth of data and imagery that are central to the European Union's Copernicus environmental programme.

The European Commission leads and coordinates this programme, to improve the management of the environment, safeguarding lives every day. ESA is in charge of the space component, responsible for developing the family of Copernicus Sentinel satellites on behalf of the European Union and ensuring the flow of data for the Copernicus services, while the operations of the Copernicus Sentinels have been entrusted to ESA and EUMETSAT.